The dependency of threshold voltage on adjusted bias voltage is varied between N-channel and P-channel MOSFETs. A support substrate, an insulating layer on the support substrate, and island-shaped first and second silicon layers separately formed on the insulating layer; a first MOSFET formed of a fully depleted SOI where a first channel part is formed in a first silicon layer; and a second MOSFET formed of a partially depleted SOI where a second channel part is formed in a second silicon layer, the second MOSFET configures a complementary MOSFET with the first MOSFET, are provided. The threshold voltage of the second MOSFET formed of the partially depleted SOI is hardly varied because of a neutral region in the second channel part, although bias voltage is applied to the support substrate to vary the threshold voltage of the first MOSFET formed of the fully depleted SOI.